Not working to connect to IRC server

Problem Description

A clear and concise description of what the bug is.

Steps to reproduce the behavior:

1. Enabled this in the systemd service for autobrr in Debian:

[Service]
Environment="GODEBUG=x509ignoreCN=0,http2client=0"
Environment="SSL_CERT_FILE=/root/.mitmproxy/mitmproxy-ca-cert.pem"
ExecStart=/opt/autobrr/autobrr --config=/opt/autobrr/config/

2. Use autobrr to setup the proxy in the settings page then add IRC network and enable proxy for it.

3. run mitmdump --mode socks5 --listen-port 1081
   127.0.0.1:51424: client connect
   127.0.0.1:51424: server connect autobrr.com:443 (75.2.60.5:443)
   127.0.0.1:51424: GET https://autobrr.com/
   << 200 OK 2.7k
   127.0.0.1:51424: client disconnect
   127.0.0.1:51424: server disconnect autobrr.com:443 (75.2.60.5:443)
   127.0.0.1:51066: client connect
   127.0.0.1:51066: server connect irc.torrentleech.org:7021 (51.210.96.245:7021)
   127.0.0.1:51066: Unexpected data from server: b'ERROR :Closing Link: [myIP] (Registration Timeout)\r\n'
   127.0.0.1:51066: server disconnect irc.torrentleech.org:7021 (51.210.96.245:7021)
   127.0.0.1:51066: Client closed connection before completing request headers: b'NICK username_autobrr\r\nUSER username_autobrr s e username_autobrr\r\n'
   127.0.0.1:51066: client disconnect

I can connect to IRC fine without the proxy

System Information

./mitmproxy --version
Mitmproxy: 11.1.3 binary
Python:    3.13.2
OpenSSL:   OpenSSL 3.4.1 11 Feb 2025
Platform:  Linux-6.1.0-33-arm64-aarch64-with-glibc2.36

Checklist

• This bug affects the latest mitmproxy release.

No source files or tests are named. Start by reproducing the Debian systemd configuration with mitmdump in SOCKS5 mode, comparing proxied and direct IRC connections. Done means identifying why the proxied IRC connection times out and verifying the corrected behavior without regressing direct connections.